Exhaust gas recirculation (EGR) is a known technique for use in internal combustion engines (petrol or diesel) wherein a portion of an engine's exhaust gas is recirculated back to the engine cylinders and mixed with the flow of intake air. EGR may be used to reduce emissions of undesirable pollutant gases, such as nitrous oxides including NO and NO2, and particulates, such as soot.
A typical EGR system may include a conduit, or other structure, fluidly connecting a portion of the exhaust path of an engine with a portion of the air intake system of the engine, thereby forming an EGR path. The exhaust gas and intake air need to be sufficiently well mixed to provide an even concentration of the exhaust gas in the intake air to enable the reduction of emissions, in particular nitrous oxides.
An EGR mixer module may be used to effect the mixing of the exhaust gas and intake air and which may be configured to mix the intake air together with the EGR gas to create a mixture having a desirable level of homogeneity. The EGR mixer module may simply be a conduit and/or the intake manifold, which may be provided with features such as for example vanes, valves, or labyrinths to increase the mixing characteristics if desired. In some embodiments the EGR mixer module may include a dedicated fluid mixer assembly.
WO 2009/149868 describes an exhaust gas mixing system having a mixing module comprising a tube with a number of apertures through which the exhaust gas flows to be distributed into the air intake channel.